Purification of murine IgG3 and IgM monoclonal antibodies by euglobulin precipitation

Abstract We describe a simple and efficient non-chromatographic method for the purification of murine IgG3 and IgM monoclonal antibodies (MAbs) which takes advantage of their euglobulin properties. Following filtration, ascitic fluid is dialysed against demineralized water and centrifuged at 22000 × g for 30 min. The resulting precipitate is dissolved in a high salt buffer (0.1 M Tris-HCl, 1 M NaCl, pH 8). A second cycle of dialysis and centrifugation yields a product of high purity. Nine IgG3 MAbs and eigth IgM MAbs were purified by this procedure. Recovery was > 90% for seven of nine IgG3 MAbs. It was less reproducible for IgM MAbs and ranged from 40% to > 90% depending on antibody and batch. Purity was assessed by SDS-polyacrylamide gel electrophoresis. The purified immunoglobin was essentially free of albumin, transferrin, and other mouse ascites proteins. No loss of antibody function was observed.